13,241 research outputs found

    ARES v2 - new features and improved performance

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    Aims: We present a new upgraded version of ARES. The new version includes a series of interesting new features such as automatic radial velocity correction, a fully automatic continuum determination, and an estimation of the errors for the equivalent widths. Methods: The automatic correction of the radial velocity is achieved with a simple cross-correlation function, and the automatic continuum determination, as well as the estimation of the errors, relies on a new approach to evaluating the spectral noise at the continuum level. Results: ARES v2 is totally compatible with its predecessor. We show that the fully automatic continuum determination is consistent with the previous methods applied for this task. It also presents a significant improvement on its performance thanks to the implementation of a parallel computation using the OpenMP library.Comment: 4 pages, 2 Figures; accepted in A&A; ARES Webpage: www.astro.up.pt/~sousasag/are

    Graviton resonances on two-field thick branes

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    This work presents new results about the graviton massive spectrum in two-field thick branes. Analyzing the massive spectra with a relative probability method we have firstly showed the presence of resonance structures and obtained a connection between the thickness of the defect and the lifetimes of such resonances. We obtain another interesting results considering the degenerate Bloch brane solutions. In these thick brane models, we have the emergence of a splitting effect controlled by a degeneracy parameter. When the degeneracy constant tends to a critical value, we have found massive resonances to the gravitational field indicating the existence of modes highly coupled to the brane. We also discussed the influence of the brane splitting effect over the resonance lifetimes.Comment: 15 pages, 8 figure

    Response to tilted magnetic fields in Bi2Sr2CaCu2O8 with columnar defects: Evidence for transverse Meissner effect

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    The transverse Meissner effect (TME) in the highly layered superconductor Bi2Sr2CaCu2O(8+y) with columnar defects is investigated by transport measurements. We present detailed evidence for the persistence of the Bose-glass phase when H is tilted at an angle theta < theta_c (T) away from the column direction: (i) the variable-range vortex hopping process for low currents crosses over to the half-loops regime for high currents; (ii) in both regimes near theta_c(T) the energy barriers vanish linearly with tan(theta) ; (iii) the transition temperature is governed by T_{BG}(0) -T_{BG}(theta) sim |tan(theta)|^{1/\nu_{\perp}} with \nu_{\perp}=1.0 +/- 0.1. Furthermore, above the transition as theta->\theta_c+, moving kink chains consistent with a commensurate-incommensurate transition scenario are observed. These results thereby clearly show the existence of the TME for theta < theta_c(T).Comment: 4 pages, RevTeX, 5 EPS figure

    Effect of field tilting on the vortices in irradiated Bi-2212

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    We report on transport measurements in a Bi-2212 single crystal with columnar defects parallel to the c-axis. The tilt of the magnetic field away from the direction of the tracks is studied for filling factors f=B_z/B_phi<1. Near the Bose Glass transition temperature T_BG, the angular scaling laws are verified and we find the field independent critical exponents nu'=1.1 and z'=5.30. Finally, above H_perpC we evidence the signature of a smectic-A like vortex phase. These experimental results provide support for the Bose Glass theory.Comment: 2 pages LaTeX, 2 EPS figures, uses fleqn and espcrc2 style macros. Submitted to Proceedings of M2S-HTSC-V

    From stellar to planetary composition: Galactic chemical evolution of Mg/Si mineralogical ratio

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    The main goal of this work is to study element ratios that are important for the formation of planets of different masses. We study potential correlations between the existence of planetary companions and the relative elemental abundances of their host stars. We use a large sample of FGK-type dwarf stars for which precise Mg, Si, and Fe abundances have been derived using HARPS high-resolution and high-quality data. A first analysis of the data suggests that low-mass planet host stars show higher [Mg/Si] ratios, while giant planet hosts present [Mg/Si] that is lower than field stars. However, we found that the [Mg/Si] ratio significantly depends on metallicity through Galactic chemical evolution. After removing the Galactic evolution trend only the difference in the [Mg/Si] elemental ratio between low-mass planet hosts and non-hosts was present in a significant way. These results suggests that low-mass planets are more prevalent around stars with high [Mg/Si]. Our results demonstrate the importance of Galactic chemical evolution and indicate that it may play an important role in the planetary internal structure and composition.Comment: Accepted by A&A (Letter to the Editor

    New framework of assessing the impacts of companies on regional sustainable development: The Sakha case

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    his paper is based on the proposed hypothesis: the activities of a company (especially a large, backbone company) in the social, environmental and economic spheres have a corresponding impact on certain aspects of the sustainable development of the region. The goal of the study is to prove this relationship at a conceptual level using indicators of sustainable development applied at different levels of socio-economic systems. The paper addresses a relevant gap in the literature: the absence of frameworks allowing the assessment of the interactions and intendancies between levels. To do this, the literature on this issue was studied and it was proved that there were no studies with a similar framework. The study draws on the systems of sustainable development indicators, suggested in literature and used for the assessment of sustainable development at the regional and company's level and proposes a framework to integrate them. For that it uses the classical balance scorecard (BSC) tools - the strategic maps both for a region and a company. The Republic of Sakha (Yakutia) in Russian Federation and public joint stock company “ALROSA” were chosen as the basic object of research at the regional and corporate level, respectively. The built strategic maps reflect the decomposition of the main strategic goal and contain an interdependent set of sustainable development indicators for each level, which can be used to assess and monitor the results of the relevant strategies. Then, a new conceptual framework reflecting the impact of the l company's activities on the sustainable development of the region is proposed. The framework includes the performance indicators of the company and the region by three dimensions of sustainable development - environmental, social, and economic. On the basis of the conceptual scheme of the relationship, it is possible in the future to build econometric models based on the proposed indicators. The identified quantitative assessments in this case will make it possible to make strategic management decisions that will maximize the positive effect of the implementation of the sustainable development strategy in the region using the potential of companies.info:eu-repo/semantics/publishedVersio
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